Embossing tools usually are made of nickel, copper, an alloy or other types of composite materials. Nickel is the most widely used material for embosser fabrication.
There are a few problems associated with the currently available embossing tools, in particular, incomplete release of the cured material or hot embossed material from the embossing tool, after embossing.
There are ways to modify the surface of an embossing tool to reduce the adhesion between the surface of the embossing tool and the cured or hot embossed material. Such methods may include silane-coating, silicone resin coating, teflon-coating, or nickel-teflon composite plating. Unfortunately, all of them failed to produce satisfactory results.
Silicone resin and teflon can be applied to the surface of the embossing tool via wet-coating. However, after drying and curing, the thickness uniformity of the coating on the surface of microstructure is poor which may change the shape of the resulting microstructures on the embossing tool.
The teflon-coating via physical vapor deposition (PVD) or chemical vapor deposition (CVD) has shown poor throwing-power and also non-uniform coverage when the microstructure on the surface of the embossing tool has a high aspect ratio. In addition, poor durability and mechanical strength of the teflon-coating is another concern, especially if an embossing tool needs to be extensively used for mass production.
Nickel-teflon composite coating can be applied to the surface of the embossing tool via electroplating or an electro-less plating process. However, the minimum coating thickness normally is several microns. Therefore, if an embossing tool has a microstructure with small dimensions, especially narrow trenches, on its surface, such coating may drastically change the profile and aspect ratio of the microstructure, rendering the embossing task much more difficult.